Too slow to choose a level (on level selection). You should put more levels on the same page. Awards are not explained. Levels too easy. I don't see the progression of difficulty. If someone is stuck on a level, he can't pass the level. It should allowed to pass one or two level in case that happenned. Not bad, can be better.
I like the idea, but I don't like the way letters were hidden. I would prefer that letters were inserted as a part of images instead of only a shade in images. I had difficulty to see some letters even if I used clues. If this game is for learning japenese, you should hide some letters inside a writing part of images. Mayby, put images of text with drawings with some letters to find.